Regulated presser mechanisms for sewing machines



R. P. GRAHAM 3,2Q4fi4? REGULATED PRESS'ER MECHANISMS FOR SEWING MACHINESDec. 27, 19M? 2 Sheets-Sheet 1 Filed April 14, 1965 INVENTOR. Richard PGraham TORNEY R. P. GRAHAM Dec. 27, 1966 REGULATED PRESSER MECHANISMSFOR SEWING MACHINES Filed April 14, 1965 2 Sheets-Sheet B INVENTOR.Richard P. Graham- WA Kim ATTORNEY WITNESS United States Patent3,294,047 REGULATED PREdSER MECHANISMS FQR SEWENG MACHHNES Richard P.Graham, Westtield, N.J., assignor to The Singer 'Company, New York,N.Y., a corporation of New Jersey Filed Apr. 14, 1965, Ser. No. 448,2119 Claims. (Cl. 112235) This invention relates in general to sewingmachines, and more particularly, the invention provides improvedadjustable apparatus for precisely regulating the pressure with which asewing machine presser-foot is brought to bear against a work-fabric.

In providing the pressure regulation feature of the invention, use hasbeen made of cooperating non-precision parts which are so arranged thatthey may provide (with considerable exactness) a particular minimalpresser-foot pressure as is necessary during certain sewing operations.As a corollary to this, therefore, it may be said that the inventionprovides manufacturing advantages, whereby quality finished products maybe provided at minimal cost. Adjustable mechanisms for regulating thepressure with which a presser-foot engages a work-fabric are wellknownin the art (as exemplified by US. Patent 3,055,326, issued September 25,1962, in the name of Robert G. Greulich); and while such mechanisms areuseful for most sewing operations, advantages in the sewing machine art,viz. work-fabric positionin apparatus as may be used in the automaticmaking of buttonholes, have necessitated that an easily settableposition of parts be made available, in which the presser foot may befree of the usual spring pressure throughout a precise range ofelevation so as to prevent flagging of the work-fabric being sewn,without impeding shift of the work fabric. Presser-foot apparatusembodying the invention provides for a position of parts having theabove-noted close dimensional tolerance requirements, and as will becomeapparent in the following description, such apparatus does so in a waythat is compatible with, and makes use of, the general pressureregulation technique described in the above-noted patent.

Accordingly, it is an object of the invention to provide improvedapparatus for regulating the pressure with which a sewing machinepresser-foot is brought to bear against a work-fabric.

Another object of the invention is to provide an improved way ofregulating, to a particular precise dimensional amount, the degree offreedom of a sewing machine presser-foot from the influence of the usualdownward spring pressure.

Another object of the invention is to provide apparatus for use inregulating presser-foot pressure, which apparatus employs both anon-precision cam and a cam follower in cooperation therewith, but whichcam and follower are so arranged that vertical movement withinexceedingly close tolerances may be provided to the presserfoot free ofdownward spring pressure.

The invention will be described with reference to the figures wherein:

FIG. 1 is a side elevational view, partly in section, of a sewingmachine embodying the invention,

FIG. 2 is a front elevational view, partly in section, of the machinedepicted in FIG. 1, such view being taken generally along line 22 ofFIG. 1,

FIG. 3 is a perspective view of the presser-foot pressure regulatingmechanism incorporated into the machine illustrated in FIGS. 1 and 2,and

FIG. 4 is a view useful in illustrating the operation of the pressureregulating mechanism of FIG. 3.

3 ,294,047 Patented Dec. 27, 1966 Referring now to the drawings, asewing machine is shown having a machine frame including a sewing head10 supported to overhang a cloth supporting plate 12 in conventionalmanner. A presser-foot 14, the applied pressure of which is variable, isadapted to urge a work-fabric against the teeth of a feed-dog 16,whereby not only may the work-fabric be moved along for continuoussewing, but pressure may be exerted against the work-fabric to preventflagging. The presser-foot 14 is detachably secured to a presser-bar 18by means of a knurled screw 20 and the presser-bar 18 is slidablysupported in a journal 22 which is itself secured to the sewing head 10by means of a screw 24. Running along the length of the presserbar 18and terminating at a location 26 is an axial bore 28, such bore 28serving to house a coil spring 30. A spring abutting bar 32, slidablyand partially contained within the bore 28, exerts a force (variable ina manner to be described later) against the spring 30 whereby the springpresses against the end 26 of the bore 28 to urge the presser-foot 14against the Work-fabric. The abutting bar 32 is slidably supported in abushing 34 that is formed with a collar 36 (to prevent axial motionthereof), and such bushing 34 is fixedly secured within a support 38formed within the sewing head 10.

The support 38 is provided with a slot 40 into which is located theshaped end 42 of a lever 44, and the lever end 42 is brought to bearagainst the tip 46 of the abutting bar 32. The lever 44 is pivotallysecured to a support 43 on the machine frame by means of an arm 50 and ascrew 52 serving as a fulcrum for the lever 44. The lever 44 is providedwith a cam follower element 54 that cooperates with a spiraled shell cam56 having as many detents 58 as there are desired discrete pressuresettings for the presser-foot 14. The cam 56 is secured to a pressureselector wheel 60 having thereon appropriate pressure representativeindicia 61, and the whole wheelcam assembly is supported, by the sewinghead 14 for rotation about an axis 62, whereby the cam 56 and itsfollower 54 cooperate to cause the lever end 42 to bear more or lessagainst the end 46 of the abutting bar 32 to cause the presser-foot 14pressure to vary as desired. The selector wheel 60 in FIG. 1 is shownset for an intermediate presser-foot pressure, i.e. the cam follower 54is shown engaging a detent 58 midway between the extreme ends of thespiraled cam surface, and clockwise and counterclockwise rotations(looking at FIG. 1) of the selector wheel 60 operate respectively toincrease and decrease presser-foot pressure.

The different radii of the detents 58 provide approximately one halfinch travel of the lever end 42, and this considerable motion of thelever end can result in a range of presser-foot pressures ofapproximately 1 to 12 pounds, despite considerable variation in thedimensions of the rod 32, the spring 30 and the bore 28. Since theseparts, as Well as the support for the lever 44 and for the cam 56, neednot be machined to close tolerances in order to provide a completelysatisfactory range of presser-foot pressures using the detents 58, thepresser mechanism may be produced inexpensively.

When the sewing machine is to be used with a work shifting device otherthan the feed dog 16, as for instance when buttonholing, darning, orembroidering, it becomes necessary that the presser foot 14 merely restupon the work with its own weight i.e., the weight of the presser-foot14, presser bar 18, spring 30 and rod 32 so as not to impede feeding ofthe work. In this type of sewing the feed dog is deactivated and thepresser-foot serves only to prevent movement of the work upwardly withthe needle or flagging as it is termed in the art. It becomes necessaryfor this type of sewing that the presser-foot be free of spring pressureuntil the presserfoot is raised a predetermined distance, preferably adistance equal to the maximum thickness of work fabric which the sewingmachine may reasonably be expected to accommodate.

If one of the detents 58 of the cam 56 is used to provide this settingof the presser mechanism for darning embroidery or buttonholing, i.e.,freedom of pressure of the spring 30 for a specific dimensionalelevation of the presser-foot, the dimensions of each and every part ofthe presser mechanism would have to be manufactured to exceedingly closetolerances and the cost of manufacture would become prohibitive.

Accordingly, the present invention proposes that, at a discrete locationon the cam 56, a detent 64 be cut which is so deep that the cam follower54 cannot engage the surface of the cam; then by means of a simplefactoryadjustment of a screw 66 threaded through the support 48, theeffective depth of the detent 6 4 may be precisely varied to provide theexact dimension of presser-foot elevation prior to the application ofspring pressure as noted above. That is, with the follower 54 sitting inthe deeply cut detent 64, the screw 66 is brought to bear against a boss67 on the lever 44 (see FIG. 4) until the degree of freedom ofpresser-foot movement is set as desired. Hence, the objects of theinvention are achieved.

A lifting mechanism for raising the presser-foot 14 for removal ofwork-fabric and the like has a lever 68 external the sewing head 10,such lever 68 being secured to one end of a shaft 70 that is rotatablysupported by the head 10. The other end of the shaft 70 locates withinthe sewing head 10 and fixedly supports a cam 72, the knee 74 of whichis aligned to bear against a boss 76 located on a member 78. The member78 is provided with a clamp 80 which fixedly secures the member 78 tothe presser-bar 18; in addition, the member 78 is formed with a tang 82that is adapted to be slidably housed in a slot 84 in the support 38,whereby rotation of the presserbar 18 about its own longitudinal axis isprevented. A light compression spring 86 i.e., a spring having a verylow spring constant may be supported coaxially with the presser-bar 18so as to bear against the clamp 80. The spring 86 acts to bias thepresser-foot 14 downwardly into the position in which it is shown inFIGS. 1 and 2 and provides for a light downward bias upon theresser-foot when the detent 64 is moved opposite to the cam follower 54.To raise the presser-foot 14, the lever 68 is (looking at FIG. 1)rotated counterclockwise, causing the knee 74 of the cam 72 to urge theboss 74 and the presser-bar 18 upward against the compression of thesprings 30 and 86; to hold the presser-foot in its raised position, thecam 72 is rotated until its fiat portion 88 engages the boss 74; inreturning the presser-foot to the position shown in FIG. 1, the lever 68is rotated clockwise, thereby enabling the springs to relax, and in sodoing return the presser-foot 14 to the position shown.

While the invention has been described in its preferred embodiment, itis to be understood that the words which have been used are words ofdescription rather than of limitation and that changes within thepurview of the appended claims may be made without departing from thetrue scope and spirit of the invention in its broader aspects.

Having thus described the nature of the invention, what I claim hereinis:

1. In a sewing machine having a machine frame, a Presser-rod pressureregulating mechanism comprising a lever supported by said machine frame,a cam and cam follower in cooperation with said lever for pivotallymoving aid lever about its fulcrum, resilient means cooperating with andheld under tension by said lever for longitudinally urging saidpresser-rod in a direction tending to relax said tension, the face ofsaid cam being provided with a recess sufficiently deep to preventcontact between said follower and said cam, and adjustable means for usein cooperating with said lever when said follower resides in said recessto adjust the force by which said lever holds said resilient means undertension.

2. The apparatus of claim 1 wherein said adjustable means is a screw,and wherein said machine frame is provided with a tapped holetherethrough for said screw, said hole in said machine frame being sopositioned that said screw may contact and pivotally move said leverabout its fulcrum in opposition to the tension in said resilient means.

3. Apparatus for use in regulating the pressure exerted by a sewingmachine presser-foot comprising a presserbar adapted to have saidpresser-foot secured thereto, means supporting said resser-bar forsliding motion that is substantially in the direction of thelongitudinal axis of the presser-bar, resilient means for use inurgingsaid presser-bar slidably in the direction of the end of thepresser-bar that is adapted to have said presser-foot secured thereto,and means for varying the tension in said resilient means comprising apivotable lever adapted to bear against said resilient means, a cam anda cam follower cooperating with said lever to vary the force with whichsaid lever bears against said resilient means, said cam being providedwith a detent therein which is sufiiciently deep to prevent engagementof said follower with said cam, and adjustable means for use in urgingsaid lever against said resilient means when said follower resides insaid detent, whereby an increment of movement of said presser-foot freeof tension from said resilient means may be precisely varied.

4. The apparatus of claim 3 wherein said presser-bar is provided with anopen bore running part way along the length of said presser-bar towardthe end thereof adapted to support a presser-foot, and wherein saidresilient means comprises a coil spring constrained coaxially with andwithin said presser-rod bore, and an abutting bar slidably movablewithin said bore and bearing against said spring.

5. The apparatus of claim 4 wherein said adjustable means is a screwablyvariable member that is aligned for pivotally moving said lever againstthe tension of said constrained coil spring.

6. In combination with a sewing machine, apparatus for varying bydiscrete amounts the pressure applied by the presser-foot of saidmachine, one discrete presser-foot pressure level provided being at aparticular predetermined low level, comprising a presser-bar having alongitudinal bore that opens at only one of its ends, the other end ofsaid presser-bar being adapted to support said presser-foot, meansforming part of said machine for supporting said presser-bar for slidingmotion, an abutting bar, a coil spring bearing against said abutting barand so constrained within said bore by said abutting bar that thelongitudinal axes of the bore and said spring are substantiallycoincidental, part of said abutting bar being slidably supported withinsaid bore, a lever adapted to bear against the end of the abutting barthat is free of said bore to compress said spring and thereby hold saidpresserfoot under pressure, said lever being pivotally secured to saidmachine and being formed with a cam follower element, a cam supported bysaid machine to engage said follower, said cam having a plurality ofdiscretely located detents one of which is sufficiently deep to preventengagement of the cam and its follower, and screwably adjustable meansfor use in pivotally positioning said lever against the compressivetension in said spring when said cam follower element resides in saidsufiiciently deep detent.

7. In combination with a sewing machine, apparatus for varying bydiscrete amounts the pressure applied by the presser-foot of saidmachine, one discrete resser-foot pressure level provided being at aparticular predetermined low level, comprising a presser-bar having alongitudinal bore that opens only at one of its ends, the other end ofsaid presser-bar being adapted to support said resser-foot, meansforming part of said machine for supporting said resser-bar for slidingmotion, an abutting bar, a coil spring bearing against said abutting barand so constrained within said bore by said abutting bar that thelongitudinal axes of the bore and said spring are substantiallycoincidental, part of said abutting bar being slidably supported withinsaid bore, a lever adapted to bear against the end of the abutting barthat is free of said bore to compress said spring and thereby hold saidpresser-foot under pressure, said lever being pivotally secured to saidmachine and being formed with a cam follower element, a pressureselector wheel having peripherally located pressure representativeindicia thereon and being supported for rotation by said machine, a camsecured to said Wheel, said cam being situated to engage said followerand having a plurality of discretely located detents one of which issufficiently deep to prevent engagement of the cam and its follower, ascrew, and a brace supported Within said machine, said brace having atapped hole therethrough for said screw that is so positioned withrespect to said brace that said screw when in said hole may Contact andmove said lever pivotally against the compressive tension of said springwhen said cam follower element resides in said sufiiciently deep detent.

8. The apparatus of claim 7 including first means for preventing saidpresser-bar from rotating about its longitudinal axis, and second meansfor raising said presserbar from the position needed for sewing.

9. The apparatus of claim 8 wherein said machine is provided with aslot, wherein said first means is a member secured to said presser-bar,said member having a tang thereon adapted to ride in said slot, andwherein said second means comprises a cam, a cam follower on said memberaligned with said cam, and a lever for rotating said cam to urge saidfollower and said member upward.

References Cited by the Examiner UNITED STATES PATENTS 2,344,414 3/1944Ritter 112-235 2,419,494 4/ 1947 Knaus 112235 3,055,326 9/1962 Greulich112-235 PATRICK D. LAWSON, Primary Examiner.

1. IN A SEWING MACHINE HAVING A MACHINE FRAME, A PRESSER-ROD PRESSUREREGULATING MECHANISM COMPRISING A LEVER SUPPORTED BY SAID MACHINE FRAME,AL CAM AND CAM FOLLOWER IN COOPERATION WITH SAID LEVER FOR PIVOTALLYMOVING SAID LEVER ABOUT ITS FULCRUM, RESILIENT MEANS COOPERATING WITHAND HELD UNDER TENSION BY SAID LEVER FOR LONGITUDINALLY URGING SAIDPRESSER-ROD IN A DIRECTION TENDING TO RELAX SAID TENSION, THE FACE OFSAID CAM BEING PROVIDED WITH A RECESS SUFFICIENTLY DEEP TO PREVENTCONTACT BETWEEN SAID FOLLOWER AND SAID CAM, AND ADJUSTABLE MEANS FOR USE